1. Field of the Invention
The present invention relates to an ink-jet recording apparatus configured to record an image and the like on a recording medium.
2. Discussion of Related Art
There has been conventionally known the so-called serial-type ink-jet recording apparatus which has an ink-jet head with a plurality of nozzles arranged in one direction and which is configured to record an image and the like on a recording medium by ejecting ink droplets from the nozzles while the ink-jet head is moved in a direction (a scanning direction) intersecting the nozzle arrangement direction.
In the known ink-jet recording apparatus described above, there may be some cases wherein the ink-jet head is attached in a posture in which the ink-jet head is inclined or rotated relative to a normal posture in a plane that is parallel to a nozzle-arranged surface (a droplet ejecting surface) in which a plurality of nozzles are formed and which is to be opposed to a recording medium, due to assembling errors or the like. In such cases, rows of the nozzles are inclined relative to a normal nozzle arrangement direction, and rows of dots formed by the nozzle rows on the recording medium are also inclined, undesirably degrading the image quality. To deal with this, it is needed to first detect inclination of the ink-jet head (inclination of the nozzle rows) and to subsequently take some measures such as adjusting the posture of the ink-jet head such that the nozzle rows extend along the normal nozzle arrangement direction or adjusting ejection timings of the nozzles in accordance with the inclination of the nozzle rows.
There has been known a technique relating to detection of the inclination of the ink-jet head. In the technique, a dot row is initially formed on the recording medium by ejecting ink from three nozzles (one nozzle group) among a plurality of nozzles in one nozzle row while the ink-jet head is moved in one of opposite two directions in the scanning direction. The three nozzles (the one nozzle group) are located at the upstream portion of the one nozzle row in the conveyance direction. Subsequently, after the recording medium has been conveyed by a prescribed amount, another dot row is formed so as to be located adjacent to the dot row previously formed by the upstream-side nozzle group by ejecting the ink from another three nozzles (another nozzle group) among the plurality of nozzles in the one nozzle row while the ink-jet head is moved in the same direction as described above. The above-indicated another three nozzles (another nozzle group) are located at the downstream portion of the one nozzle row in the conveyance direction.
Here, where the nozzle row is inclined relative to the normal direction, there occurs a position shift in the scanning direction in accordance with the inclination of the nozzle row, between the dot row formed by the upstream-side nozzle group and the dot row formed by the downstream-side nozzle group. In view of this, in the above known technique, there is detected a distance (position shift) in the scanning direction between the dot row formed by the upstream-side nozzle group and the dot row formed by the downstream-side nozzle group. On the basis of the detected distance, the ejection timing of each of the nozzles of the nozzle row is adjusted, thereby eliminating the influence of the inclination of the nozzle row on the image quality.